Hey neo,
I don't have any articles, but your question doesn't seem like it's very quantifiable. I just don't think anyone can tell you that "X amount of cardio is going to result in X amount of heart enlargement using X dosage of desoxymethyltestosterone". I don't think enough studies have been done on such a thing (but I could be wrong).
And anyone telling you how they subjectively feel after using phera with and/or without cardio that haven't actually had their heart monitered throughout is purely conjecture. From what I've read heart size should return to normal following a cycle. I know there is one study floating around the board related to an increase in heart size with phera plex which is probably the reason why you posted this to begin with. But other than that, I have not read any studies regarding phera plex and the heart. Maybe others will chime in and prove me wrong here though.

Desoxymethyltestosterone (DMT), also known as Madol, is a steroid recently identified to be misused as a doping agent. Since, the knowledge of functions of this substance is rather limited, it was our aim to characterise the pharmacological profile of DMT and to identify potential adverse side effects. DMT was synthesised, its purity was confirmed and its biological activity was tested. The potency of Madol (DMT) to transactivate androgen receptor (AR) dependent reporter gene expression was two times lower as compared to dihydrotestosterone (DHT). Receptor binding tests demonstrate that DMT binds with high selectivity to the AR, binding to the progesterone receptor (PR) was low. In vivo experiments in orchiectomised rats demonstrated that treatment with DMT resulted only in a stimulation of the weight of the levator ani muscle; the prostate and seminal vesicle weights remained unaffected. Like testosterone, administration of DMT resulted in a stimulation of IGF-1 and myostatin mRNA expression in the gastrocnemius muscle. In the prostate proliferation was stimulated by TP (testosteronepropionate), but remained unaffected by DMT. Remarkably, treatment with DMT, in contrast to TP, resulted in a significant increase of the heart weight. In the liver, DMT slightly stimulates the expression of the tyrosine aminotransferase gene (TAT). Our results demonstrate that DMT is a potent AR agonist with an anabolic activity. Besides the levator ani weight, DMT also modulates the gene expression in the musculus gastrocnemius. The observed stimulation of TAT expression in the liver and the significant increase of the heart weight after DMT treatment can be taken as an indication for side effects. Summarizing these data it is obvious that DMT is a powerful anabolic steroid with selective androgen receptor modulators (SARM) like properties and some indications for toxic side effects. Therefore, there is a need for a strict control of a possible misuse